1. Field of the Invention
The present invention relates to a spindle motor employed for rotating and driving a disk or the like.
2. Description of the Related Art
There has been conventionally known a motor of such a type that a stator is supported and fixed to a flange on which a shaft is fixedly supported and a rotor provided with a magnet in its inner periphery is rotatably supported by the shaft while the magnet is opposed with a predetermined interval to the outer periphery of the stator. In this motor, the rotor rotates on the outer periphery of the stator in accordance with the interaction between magnetic flux generated from a coil provided in the stator and magnetic flux generated from the magnet.
In such an outer rotor type spindle motor, since the outside diameter of the rotor becomes large in view of its structure, the moment of inertia thereof increases to reduce the unevenness of rotation. Therefore, this spindle motor is particularly suitable to a motor for rotating and driving a disk storage medium such as a magnetic disk used as a storage medium of a computer.
However, in the above mentioned conventional spindle motor, since each of the stator and the shaft comes into direct contact with the flange and is fixedly supported to the flange, there have been encountered such problems as mentioned below.
First, since the stator comes into direct contact with the flange and is fixedly supported to the flange, electromagnetic vibration and vibration caused from a rotating action which are generated in the stator by an alternating current supplied to the coil (stator coil) of the stator are directly transmitted to the flange.
Further, since the shaft comes into direct contact with the flange and is supported by and fixed to the flange, the vibration due to the rotation of the rotor which the shaft receives (rotating vibration) is, inconveniently, transmitted directly to the flange as it is.
Therefore, the electromagnetic vibration and the vibration caused from the rotating action from the stator and the rotating vibration from the shaft are both transmitted to the flange as they are, so that the vibration is doubled. Further, a larger vibration is sometimes generated due to the interaction of both the vibrations, or due to resonance with the flange or the like, which undesirably causes generation of noise.
The present invention was made in order to solve the problems of the above-mentioned prior art and it is an object of the present invention to provide a spindle motor in which the transmission of electromagnetic vibration and vibration caused from a rotating action from a stator or rotating vibration from a shaft to a flange can be suppressed and the generation of vibration, especially, the generation of large vibration or noise in the flange, can be prevented.
In order to achieve the above-mentioned object, according to a first aspect of the present invention, there is provided a spindle motor comprising: a flange for supporting and fixing a shaft; a stator supported by and fixed to the flange; and a rotor provided with a magnet in its inner periphery, the rotor being rotatably supported by the shaft in a condition where the magnet is opposed with a predetermined interval to the outer periphery of the stator, the rotor rotating in accordance with the interaction between magnetic flux from a coil provided in the stator and magnetic flux from the magnet, characterized in that a damping member is interposed between the flange and the stator.
According to a second aspect of the present invention, there is provided a spindle motor comprising: a flange for supporting and fixing a shaft; a stator supported by and fixed to the flange; and a rotor provided with a magnet in its inner periphery, the rotor being rotatably supported by the shaft in a condition where the magnet is opposed with a predetermined interval to the outer periphery of the stator, the rotor rotating in accordance with the interaction between magnetic flux from a coil provided in the stator and magnetic flux from the magnet, characterized in that a damping member is interposed between the flange and the shaft.
According to a third aspect of the present invention, there is provided a spindle motor comprising: a flange for supporting and fixing a shaft; a stator supported by and fixed to the flange; and a rotor provided with a magnet in its inner periphery, the rotor being rotatably supported by the shaft in a condition where the magnet is opposed with a predetermined interval to the outer periphery of the stator, the rotor rotating in accordance with the interaction between magnetic flux from a coil provided in the stator and magnetic flux from the magnet, characterized in that each of the shaft and the stator comes into direct contact with the flange and is supported by and fixed to the flange, and in that at least portions of the flange which are in contact with the shaft and the stator, respectively, are formed of damping material.
According to a fourth aspect of the present invention, the spindle motor of the first, the second, or the third aspect of the present invention is characterized in that the rotor can be loaded with a disk storage medium, and the spindle motor is configured in such a manner as to rotate and drive a disk.
In the spindle motor according to the first aspect of the present invention, the damping member is interposed between the flange and the stator, so that the electromagnetic vibration and the vibration caused from a rotating action which are generated on the stator due to an alternating current supplied to the coil of the stator (stator coil) can be damped and absorbed by the damping member and can be prevented from being transmitted to the flange.
In the spindle motor according to the second aspect of the present invention, since the damping member is interposed between the flange and the shaft, the rotating vibration of the rotor which the shaft receives is damped and absorbed by the damping member and can be prevented from being transmitted to the flange.
In the spindle motor according to the third aspect of the present invention, at least portions of the flange which are in contact with the shaft and the stator, respectively, are formed of damping material.
Accordingly, the shaft and the stator are merely mounted on the flange without taking a trouble to interpose the damping members respectively between the flange and the shaft, and between the flange and the stator, thereby obtaining the same effect as those provided by the first and second aspects of the present invention.
In the spindle motor according to the fourth aspect of the present invention, the disk storage medium can be mounted on the rotor so that the spindle motor of the present invention is configured as a motor for rotating and driving a disk.
Accordingly, there can be obtained a motor for rotating and driving the disk storage medium provided with a characteristic that the vibration from the stator or the rotor is damped and absorbed by the damping members or portions formed of damping material as well as a characteristic of small unevenness in rotation which is originally included in the outer rotor type spindle motor.